Daniel Ellsberg, the history-making whistleblower who by leaking the Pentagon Papers revealed longtime government doubts and deceit about the Vietnam War and inspired acts of retaliation by President Richard Nixon that helped lead to his resignation, has died.

He was 92.

Ellsberg, who announced in February that he was terminally ill with pancreatic cancer, died Friday morning, according to a letter from his family released by a spokeswoman, Julia Pacetti.

Until the early 1970s, when he revealed that he was the source for the stunning media reports on the 47-volume, 7,000-page Defense Department study of the U.S. role in Indochina, Ellsberg was a well-placed member of the government-military elite.

He was a Harvard graduate and self-defined “cold warrior” who served as a private and government consultant on Vietnam throughout the 1960s, risked his life on the battlefield, received the highest security clearances and came to be trusted by officials in Democratic and Republican administrations.